Type J thermocouple table: mV vs °C (−210 to 1200 °C)

Type J thermocouple voltage in mV from −210 to 1200 °C in 10 °C steps, from the NIST (ITS-90) reference functions with the reference junction at 0 °C.

A type J thermocouple (iron (+) and copper-nickel, constantan (−)) produces a voltage that depends on the temperature difference between the measuring junction and the reference junction. The table follows the NIST (ITS-90) reference functions, with the reference junction at 0 °C.

Type J thermocouple, reference junction at 0 °C: −210 … 200 °C
°C	mV
−210	−8.095
−200	−7.890
−190	−7.659
−180	−7.403
−170	−7.123
−160	−6.821
−150	−6.500
−140	−6.159
−130	−5.801
−120	−5.426
−110	−5.037
−100	−4.633
−90	−4.215
−80	−3.786
−70	−3.344
−60	−2.893
−50	−2.431
−40	−1.961
−30	−1.482
−20	−0.995
−10	−0.501
0	0.000
10	0.507
20	1.019
30	1.537
40	2.059
50	2.585
60	3.116
70	3.650
80	4.187
90	4.726
100	5.269
110	5.814
120	6.360
130	6.909
140	7.459
150	8.010
160	8.562
170	9.115
180	9.669
190	10.224
200	10.779

Type J thermocouple, reference junction at 0 °C: 210 … 620 °C
°C	mV
210	11.334
220	11.889
230	12.445
240	13.000
250	13.555
260	14.110
270	14.665
280	15.219
290	15.773
300	16.327
310	16.881
320	17.434
330	17.986
340	18.538
350	19.090
360	19.642
370	20.194
380	20.745
390	21.297
400	21.848
410	22.400
420	22.952
430	23.504
440	24.057
450	24.610
460	25.164
470	25.720
480	26.276
490	26.834
500	27.393
510	27.953
520	28.516
530	29.080
540	29.647
550	30.216
560	30.788
570	31.362
580	31.939
590	32.519
600	33.102
610	33.689
620	34.279

Type J thermocouple, reference junction at 0 °C: 630 … 1040 °C
°C	mV
630	34.873
640	35.470
650	36.071
660	36.675
670	37.284
680	37.896
690	38.512
700	39.132
710	39.755
720	40.382
730	41.012
740	41.645
750	42.281
760	42.919
770	43.559
780	44.203
790	44.848
800	45.494
810	46.141
820	46.786
830	47.431
840	48.074
850	48.715
860	49.353
870	49.989
880	50.622
890	51.251
900	51.877
910	52.500
920	53.119
930	53.735
940	54.347
950	54.956
960	55.561
970	56.164
980	56.763
990	57.360
1000	57.953
1010	58.545
1020	59.134
1030	59.721
1040	60.307

Type J thermocouple, reference junction at 0 °C: 1050 … 1200 °C
°C	mV
1050	60.890
1060	61.473
1070	62.054
1080	62.634
1090	63.214
1100	63.792
1110	64.370
1120	64.948
1130	65.525
1140	66.102
1150	66.679
1160	67.255
1170	67.831
1180	68.406
1190	68.980
1200	69.553

What about the cold junction?

In the field the reference junction sits at the transmitter or instrument terminals, almost never at 0 °C. So the voltage measured at the terminals is not the table value: the instrument compensates the cold junction. To check a mV reading, take the terminal temperature into account.

Calculated reference values, not measurements. The thermocouple tolerance depends on its class (IEC 60584-1) and is not in the table.

Values calculated from the reference functions; they do not replace measurement or a calibration certificate.

What about the cold junction?

See also